You create a Demi Plane which allows you store inanimated objects. To put a item into the Vault you have to be in possesion of the item for at least 24 hours. The Items are not allowed to be bigger than small. The Space can hold 20 pounds and two items.You cant have more than one Vault created. If the space is overloaded the boundings becomes instabel and breaks down, its contents are scattered in the Astral Plane.
You can store magic items but placing a magical item inside that create an extradimensional space created by a bag of holding or similar item instantly destroys the item and the Vault, furthermore it opens a gate to the Astral Plane. The gate originates where you standed at the point of time where you tried to store it inside it. Any creature within 10 feet of the gate is sucked through it to a random location on the Astral Plane. The gate then closes. The gate is one-way only and can't be reopened.
To retrieve an item you need to use an action to do so, the items is summond into one free hand. 
If you die the spell gets instabel after 1d4 hours, when this happens your items a lost in the astral Plane. 

At Higher Levels. When you cast this spell using a spell slot of lvl 2 or higher the maximum weight the Vault can Hold increases by 20 per spell lvl and the maximum amount of items stored increases at a rate of 2 per spell level